Communication systems providing users thereof with a possibility for wireless communication are known. A typical example of such systems is a cellular or mobile communications system. The cellular communication system is a communication system that is based on use of radio access entities and/or wireless service areas. The access entities are often referred to as cells. A characteristic feature of the cellular systems is that they provide mobility for the users of the communication system. Hence they are often referred to as mobile communication systems.
Non-limiting examples of cellular communications systems include standards such as the GSM (Global System for Mobile communications) or various GSM based systems (such as GPRS: General Packet Radio Service), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), WCDMA (Wideband Code Division Multiple Access), TDMA/CDMA (Time Division Multiple Access/Code Division Multiple Access) in UMTS (Universal Mobile Telecommunications System), IMT 2000, i-Phone and so on.
In a cellular system, a base transceiver station (BTS) provides a wireless communication facility that serves mobile stations (MS) or similar wireless user equipment (UE) via an air or radio interface within the coverage area of the cell. As the approximate size and the shape of the cell is known, it is possible to associate the cell to a geographical area. The size and shape of the cells may vary from cell to cell. Several cells may also be grouped together to form a larger service area. A base station may provide more than one cell.
Each of the cells can be controlled by an appropriate controller apparatus. For example, in the WCDMA radio access network the base station (which may be referred to as Node B) is connected to and controlled by the radio network controller (RNC). In the GSM radio network the base station may be connected to and controlled by a base station controller (BSC) of a base station subsystem (BSS). The BSC/RNC may be then connected to and controlled by a mobile switching center (MSC). Other controller nodes may also be provided, such as a serving GPRS support node (SGSN). The MSCs of a cellular network are typically interconnected and there may be one or more gateway nodes connecting the cellular network e.g. to a public switched telephone network (PSTN) and other telecommunication networks such as to the Internet and/or other packet switched networks.
The cellular network apparatus and/or the mobile station can be employed for provision of location information of the mobile station and thus the user thereof. In an application the cells or similar geographically limited service areas and associated controller nodes facilitate the cellular communications system to produce at least a rough location information estimate concerning the current geographical location of a particular mobile station. If the location of the cell is known, it is possible to conclude therefrom the geographical area in which a given mobile station communicating in said cell is likely to be at a given moment. This information may be provided also when the mobile station is located within the coverage area of a visited or “foreign” network. The visited network may be capable of transmitting location information of the mobile station back to the home network, e.g. to support location services or for the purposes of call routing and charging.
A mobile station itself may also be provided with appropriate equipment to provide information on which the positioning of the mobile station can be based on. The mobile station may communicate the information via the base to an appropriate network element that may use the information in a predefined manner.
More accurate location information may be obtained based on various location estimation methods, e.g. based range difference (RD) measurements or by means of an external location information service, for example a satellite based system such as those referenced by the names ‘Global Positioning System’ (GPS) or ‘Galileo’. The measurements may be accomplished at the mobile station or by a number base stations.
The location information is typically provided by means of a location service functionality associated with the communication system. The location service functionality may be provided by a separate network element such as a location server which receives location information from one or more sources. If the service entity receives only an indication of the present cell (e.g. the cell ID), and no further computations and/or approximations are made, this would give the location to an accuracy of one cell, i.e. it would indicate that the mobile station is (or at least was) within the coverage area of a certain cell.
3GPP specification 3GTS 23.032 v4.0-0 titled ‘Universal Geographical Area Description’ presents a possibility for defining/representing geographical areas. The definition is based on shape and one or several location points. This concept may be referred to as DEfined Geographical Areas (DEGA). Based on this concept the mobile station measures its position. The station is adapted to compare the determined position to a defined geographical area. If it is determined that the mobile station has entered or left the defined area, the mobile station sends a notification thereof to the network.
Information that is required for the area definition is stored at the mobile station. The DEGA information may be broadcast via the base stations to the mobile stations. The DEGA information may also be stored beforehand in a SIM/USIM (subscriber identity module/UMTS SIM) of the mobile station. The DEGA information typically consists of one or several geographical points and shapes as defined by the 3GTS 23.032 specification. The DEGA information may also include a unique name, identification number of other identifier for the defined area in question.
A location-based application may be interested in when a specific subscriber is entering or leaving a geographical area. Different kinds of services are possible if such a mechanism would be in place. It might be useful for various commercial and non-commercial services and similar applications to have information if a mobile station is located within a particular defined geographical area. In some application it might be useful for the network element to be able accomplish the operation for obtaining location information only if the mobile station is detected as being in a selected part of the communication system. For example, various organisations or even individuals may want to send information and/or offer services to a mobile station only in a particular defined geographic area and/or to a certain type of subscriber in a particular geographical area. More detailed examples of these include location based push services like advertisements and parents monitoring the whereabouts of their children. It may be enough if the party requesting for information receives confirmation whether a mobile station is within the defined are or not. It would also be advantageous if the location information could be provided without causing excessive load into the resources of the communication network.
The inventors are not aware of any solutions to the above that could be implemented based on the existing standards and in which there is not a need for proprietary solutions utilizing some kind of polling schemes and/or heuristics have been proposed. All proposed solutions are based on polling mechanisms and/or they are introducing requirements for new architectural aspects to the communication standards. The earlier proposals utilize polling mechanisms and heuristics to decrease the polling intervals, as the subscriber is getting closer to the area of interest. Recently a user equipment (UE) based solution has been proposed in the 3GPP. However, this solution requires modification and/or introduction of the application running in the Subscriber Identity Module (SIM) of the mobile station and communication utilizing the SMS service. The proposal also requires introduction of new architecture in the LCS. The inventors have also found that the prior art solutions based on polling and heuristics may be too heavy (both computationally and from the point of view of the load caused to the signalling channels), especially in occasions where nothing else than information whether a specific mobile station is located or not within a specific area is required.